The performance of a skilled task requires coordinated intra-limb and inter-limb movement patterns. Performing a task a multitude of times or deviating from a specific coordinated pattern can result in an undesirable task being performed or an injury to the performer. Deviation from a desired coordination pattern can be the result of many factors including, but not limited to, performer fatigue, the skill level of the performer, difficulty of the desired task or changing environmental conditions. Knowledge relating to the position of the joints during the performance of a task can be beneficial to identify and classify patterns of movement inherent in particular tasks. When patterns of movement are identified, it is similarly desirable to identify when a particular movement has occurred, how many times that movement has occurred and several other characteristics that can describe the particular motion.
Observation, assessment and interpretation of movements are routinely used by coaches, therapists, clinicians, ergonomics engineers and biomechanists to identify patterns in joint movements. This process can be subjective and generally relies on the skill of the observer to identify relationships in joint movements, to distinguish between changes in movements and to count the amount of movements performed. Using subjective measures by an observer introduces accuracy, repeatability and validity concerns when evaluating limb movements. Further, subjective measures can be difficult to implement due to costs associated with observation time.
Instrumentation of limbs to objectively observe motions is currently used to address some of the above mentioned limitations; however, instrumentation of the limbs has limitations. For example, current methods of instrumentation of limbs can be obtrusive to the performer, costly to implement and can seldom be readily used outside a laboratory condition in a reliable manner.